1. Field of Use
This invention relates to filling machines for repeatedly dispensing relatively small predetermined quantities of flowable particulate material into containers such as boxes, cans or bags.
The material may, for example, take the form of powdered or granular industrial products such as chemicals, cleaning compounds or the like; prepared or unprepared food products such as condiments, seasonings, nuts, edible seeds and grains or the like; or agricultural or gardening products such as seeds, fertilizers or the like.
2. Description of the Prior Art
Several types of prior art filling machines of the aforesaid character are known and/or in use. One type comprises a hopper to be filled with particulate material and having a single hopper spout thereon for gravity feeding the material to a filling mechanism which repeatedly dispenses relatively small measured quantities of the material to individual containers passing beneath the mechanism. The mechanism comprises a rotatable horizontally disposed upper plate located immediately below the hopper spout and having a material receiving hole therethrough. Drive means are provided to rotate the upper plate. The mechanism also comprises a stationary horizontally disposed bottom plate located below the upper plate and having a material dispensing hole therethrough beneath which the containers pass. The dispensing hole is offset or displaced from (i.e., not in registering with) the hopper spout. When the upper plate rotates, the receiving hole passes beneath the hopper spout and momentarily stops thereat and the bottom plate cooperates with the upper plate to close off the lower end of the receiving hole and thereby define a chamber of predetermined volume into which material drops from the hopper spout. As the upper plate continues to rotate, the material-filled receiving hole passes beneath a horizontal wiping brush which has a brush surface flush with the upper surface of the upper plate. The brush operates to level off or sweep away any excess material protruding from the material-filled receiving hole so that only a predetermined measured volume of material remains in the receiving hole. As the upper plate rotates further, the material-filled receiving hole moves into registry with the dispensing hole in the bottom plate, momentarily stops thereat and the material in the receiving hole falls through the dispensing hole into a container therebeneath, whereupon upper plate rotation resumes to repeat the cycle.
The production capacity of the aforedescribed prior art filling machine can be and has been increased by providing a plurality of spaced-apart receiving holes in the upper plate which are circumferentially arranged around the axis of rotation of the upper plate. Further productivity increases have been achieved by using an upper plate having a plurality of receiving holes and by providing two or more circumferentially spaced apart hopper spouts and a corresponding plurality of circumferentially spaced apart dispensing holes in the bottom plate.
The foregoing types of prior art filling machines are generally satisfactory for their intended purposes but have certain drawbacks. For example, the need to periodically stop rotation of the upper plate as each receiving hole is filled and subsequently emptied, imposes upper limits on the rotational speed of the upper plate. Furthermore, the use of a brush to effect levelling of the material causes the excess material to be randomly scattered across the upper surface of the rotatable upper plate and this, depending on the nature of the particulate material being processed, can cause material build-up on the brush and/or clogging at the location whereat the end of the hopper spout interfaces with the relatively movable upper surface of the upper plate. In addition, if the particles in the particulate material being processed are relatively large and irregularly shaped, the brush bristles, clogged or unclogged, can randomly engage and dislodge material which should remain in a properly-filled receiving hole. Another problem in prior art machines involves leakage of powdered or finely-granulated material at the interface between the hopper spout and the upper surface of the upper plate and at the interface between the bottom of the filled receiving hole and the adjacent upper surface of the bottom plate.
It is desirable, therefore, to provide improved filling machines which overcome the aforesaid drawbacks and problems and have other advantages.